1. Field of the Invention
The present invention relates to a mobile communication system, and more particularly, to an architecture of a mobile communication system network which can make connection to the Internet/a packet network from a mobile station, transmit a signal received from the Internet/the packet network to a moving mobile station, or support data communication between mobile stations; and a method for transmitting a packet data using the same.
2. Background of the Related Art
First generation terrestrial radio data communication uses an exclusive radio data communication network or a cellular communication system provided with a modem. On the other hand, second generation terrestrial radio data communication uses combined speech/data radio data communication employing digital cellular/PCS network. In the next generation communication, it is foreseen that there will be ceaseless development of high speed radio data services in a multimedia information based communication environment. That is, in place of exclusive speech or data communication service, multimedia service of, such as speech, data, text and image based on radio mobile communication service will be on the lead. Under this situation, the next generation mobile telephone system(IMT-2000) based on the cellular/PCS radio communication system network defines a communication system network such that a radio terminal can even provide a wideband multimedia service, studies for standardizing which is underway. For the success of global roaming service, high speed radio data service, and radio multimedia service, which are basic system requirements for the next generation mobile communication network, interlock both with the Internet, which makes global service, and a packet data communication system network is an essential requirement as set forth in the standard document(Q. 1701) of the ITU(International Telecommunications Union), presently. A draft for formulating a communication system network to implement such interlock with the Internet/packet network is suggested in the standard document Q. 1701 of the ITU.
FIG. 1 illustrates a block diagram of a related art mobile communication system network suggested in the ITU standard documents Q. 1701 and Q. 1711.
Referring to FIG. 1, one user data terminal UDT1 or UD12 and one mobile terminal MT1 or MT2 connected together form a mobile station MS1 or MS2 for providing a radio Internet and a packet data services. Each base station BS1-BS3 connects the mobile station MS1 or MS2 to a radio channel. Each of radio network controllers RNC1 and RNC2 is connected to a plurality of base stations BS1 and BS2 within a cell or a sector to which it pertains for separating packet data and circuit data service paths in matching with a core network using a channel assignment function varied with an service option of the mobile stations MS1 or MS2. A packet data serving node PDSN1 or PDSN2 is a physical element having a PSCF(Packet service control function) defined in the ITU standard document Q1711. And, a PDGN (Packet data gateway node) is a physical element having a PSGCF(Packet service gateway control function). The PDSN and the PDGN are radio packet data service elements, for transmitting a packet data, which is to be transmitted from the UDT (UDT1 or UDT2) to the Internet/packet network 300, from the RNC (RNC1 or RNC2) to the Internet/packet network 300 by packet switching. Since the PDSNs (PDSN1 and PDSN2) and the PDGN should always know positional movements of the mobile terminals MT1 and MT2 for switching a packet data, the PDSNs (PDSN1 and PDSN2) and the PDGN should have a signal line always connected to VLR/HLR(Visitor location register/home location register) and maintained. Therefore, in order to support a roaming service for a mobile station roamed into other communication company and a hand off service, the PDGN in a home network and the PDSN in a visit network should be connected with an NNI(Network to network interface).
However, the related art mobile communication system network has the following problems.
First, in the mobile communication system network as shown in FIG. 1, a continuous maintenance of a signal link between the PDSN and the PDGN is prerequisit for connection to the Internet/packet network from a particular mobile station. That is, when a mobile station executes hand-off frequently, either the PDSN in the home network and the PDSN in the visit network should be connected, or the PDGN in the home network and the PDSN in a visit network should be connected. Eventually, the packet data transmission under such communication environment causes complicated tangling of communication system networks.
Second, the requirement for registration of positional information of a mobile station roamed from a home network to a visit network on the VLR/HLR causes signal traffic between the PDSN and the VLR/HLR or the PDGN and the VLR/HLR every time a position registration or position verification is executed.
Third, as shown in FIG. 1, connection both of the PDSN and the PDGN to the VLR/HLR is required for implementing a mobile station position registration, which can not but greatly increase signal links for position registration or position verification of mobile stations if a plurality of PDSNs and/or PDGNs are operative in the communication system network shown in FIG. 1, that requires additional matching devices provided separately to the VLR/HLR for reduction of the increased communication links in the related art.